It works a lot like Word's outline support, but is much more vim-compatible.
It has syntax highlighting, embedded text blocks, shortcut mappings using both LocalLeader and arrow keys, and works reasonably well with Vim Easy.
There is a toolbar that will be familiar to you if you've used Word's outliner.

You can extract just text, or just headings if you wish; there's also some converters (to HTML, Perl POD, and to RTF) included.

I could have also installed it so it would be available to all the
users on my system by putting it into either the
/usr/local/share/vim/vimfiles or /usr/local/share/vim/vim60
directories.

Installing the binaries

I've included some scripts in Perl and Ruby that I use for
conversion of .otl files to HTML, RTF, and Perl POD. There is also
a pod2otl converter.
You can move these to a directory on your path (you may also have
to change the shebang (#!) lines).